diff --git a/Makefile.am b/Makefile.am
--- a/Makefile.am
+++ b/Makefile.am
@@ -17,6 +17,7 @@
 	cmake/FindCPLEX.cmake \
 	cmake/FindGLPK.cmake \
 	cmake/FindCOIN.cmake \
+	cmake/LEMONConfig.cmake.in \
 	cmake/version.cmake.in \
 	cmake/version.cmake \
 	cmake/nsis/lemon.ico \
diff --git a/lemon/path.h b/lemon/path.h
--- a/lemon/path.h
+++ b/lemon/path.h
@@ -1015,18 +1015,20 @@
 
   /// \brief The source of a path
   ///
-  /// This function returns the source of the given path.
+  /// This function returns the source node of the given path.
+  /// If the path is empty, then it returns \c INVALID.
   template <typename Digraph, typename Path>
   typename Digraph::Node pathSource(const Digraph& digraph, const Path& path) {
-    return digraph.source(path.front());
+    return path.empty() ? INVALID : digraph.source(path.front());
   }
 
   /// \brief The target of a path
   ///
-  /// This function returns the target of the given path.
+  /// This function returns the target node of the given path.
+  /// If the path is empty, then it returns \c INVALID.
   template <typename Digraph, typename Path>
   typename Digraph::Node pathTarget(const Digraph& digraph, const Path& path) {
-    return digraph.target(path.back());
+    return path.empty() ? INVALID : digraph.target(path.back());
   }
 
   /// \brief Class which helps to iterate through the nodes of a path